I had a practice session this evening. Before working on things, I was getting 85' - 90' (measured) but it was not pretty. I spent the next 90 minutes tweaking the back cast. I think another session like that and I'll be very happy with the back cast. I didn't measure again at the end of the session, but the estimated 75' - 80' casts were MUCH better by then.
I'm confident I'll make the distance 100% of the time by the end of the month, but I think the accuracy might not be good enough for 3/5 times. I'll see.
I spent the next hour after that working on the Snakehead Shot. On grass, with a 6wt Thunderbolt, no popper - just fluff, but 18m casts were pretty easy. Next stop: poppers on water with a 10wt.